Probabilistic buckling analysis of axially loaded piles in liquefiable soils

Recent research has demonstrated that axial load alone can cause a slender pile to fail by forming a plastic hinge, if soil surrounding the pile liquefies in an earthquake. This failure mechanism is due to buckling instability. Lateral loads from lateral spreading of the surrounding soil and/or inertia and imperfection inherent in a pile result in increased deflection, which can promote more rapid collapse. These effects are secondary to the basic requirement so that axially loaded piles passing through liquefiable soils should be checked against Euler's buckling in addition to the bending mechanism of failure, i.e. incorporation of P?Δ effect. While fewer large diameter piles are currently being used in modern construction practice (which performed better in liquefiable areas rather than multiple small diameter piles), there are many pile-supported structures where buckling considerations were not taken into account and therefore may need retrofitting. This paper develops a probabilistic tool which can be used for assessing the likelihood of a buckling failure of existing piled foundations due to a scenario earthquake. This tool can equally serve as a valuable decision-support tool for implementing earthquake risk mitigation measures. A case study is presented to show the applicability of the method.